Rotor assembly



Nov. 21, 1950 LE TOURNEAU 2,531,225

v ROTOR ASSEMBLY Filed June 15, 1948 1 11 I: q 15 l s 5 H 1 a 0 11 I2 I INVENTOR R.G.Le7?9u.rnsaw BY w t/1114.121

. ATTORNEYS Patented Nov. 21, 1950 ao'roa ASSEMBLY Robert G. Le Tourneau, Longview, Ten, assignor to R. G. Le Tourneau, Inc., Stockton, Call! a corporation of California Application June 15, 1948, Serial No. 33,119

7 Claims. 1

This invention relates in general to a rotor assembly for an A. C. induction motor of high torque type; the present invention representing a modification of the induction rotor shown in copending application, Serial No. 782,380, filed October 2'7, 1947, now U. S. Patent No. 2,517,002 of August 1, 1950.

It is one object, of the present invention, to provide the rotor with a resistance end bell, of improved design, operative to attain maximum heat dissipation when the rotor is functioning in an A. C. induction motor.

It is another object, of the present invent on, to provide a resistance end bell, as above, which includes a novel fan structure whose purpose is to accelerate and improve the heat dissipating characteristics of said end bell.

A further object of the invention is to provide a resistance end bell, as in the preceding paragraph, wherein the bell is formed intermediate its ends with a circumferential row of slots for the passage of conductor bars projecting from the rotor; the fan structure comprising blades projecting inwardly from corresponding longitudinal edges of the slots in the end bell. In practice these blades are the parts of the end bell struck out to form the slots; said blades each remaining integral with the bell along one longitudinal edge and being bent inwardly therefrom.

It is also an object of the invention to provide a rotor assembly in which the rotor, conductor bars, a securing ring at one end of the rotor, and the resistance end bell at the other end of t e rotor are secured together, in a novel combina tion, to provide a rugged and reliable structure for the intended purpose.

A further object of the invention is to provide a practical and effective rotor assembly, and yet one which will be exceedingly effective for the purpose for which it is designed.

These objects are accomplished by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawings:

Fig. l is a side elevation, in section, of the rotor assembly.

Fig. 2 is an end view of the rotor assembly, looking into the resistance end bell.

Referring now more particularly to the characters of reference on the drawings, the rotor assembly comprises a laminated rotor I having a central bore 2 and ailixed, at one end, in concentric relation to an attachment hub 3. The motor shaft (not shown) is adapted to engage in the bore 2 and hub 3 in matching relation; being maintained against rotation by a key engaged in a keyway 4.

Beyond one end of the rotor I, and in surrounding relation to the hub 3, there is a resistance end hell 5 stamped from a sheet of metal, preferably stainless steel.

The resistance end bell 5 is formed with an inner endwall 6 which abuts the adjacent end of the rotor I being secured thereto and tothe hub 3 by welding, as shown at I.

From the inner endwall 6 the resistance end bell 5 flares outwardly in a direction away from the rotor I, remaining at all times concentric to the rotor axis. At its outer end the resistance end bell 5 is of greater diameter than the rotor I and the said end is formed with an annular, radially outwardly projecting stiffening flange 8. Said annular stiii'ening flange 8 is of substantial radial extent, serving to strengthen the outer end of the bell, and as an attachment part, as will hereinafter appear.

The rotor I is formed, in its peripheral portion, with a plurality ofv equally circumferentially spaced slot 9 which extend parallel to the rotor axis, and are open to opposite ends of said rotor.

A plurality of heavy-duty conductor bars Ill of copper or similar high-conductivity metal, are fitted, in matching relation, in the slots 9 and project beyond opposite ends of the rotor.

The flared portion of the resistance end bell 5 ,is formed, in substantial alinement with pairs of said conductor bars II), with rectangular slots I I each of said pairs of conductor bars projecting through the corresponding slot II adjacent opposite sides thereof.

After passing through the corresponding slot I I, the conductor bars of each pair are outturned at the ends, as at I2, and matchingly rest against the adjacent face of the annu ar stiffening flange 8 for the full width of the latter; said outturned ends I2 of the conductor bars being welded to said flange, as at I3. The outturned ends I! of each pair of the conductor bars diverge outwardly, as clearly shown in Fig. 2, so that there is substantially equidistant spacing thereof on the flange 8.

A retention ring I4 surrounds the conductor bars I 0 in overlying relation to the slots I I whereby to prevent deformation of said bars at such point when the rotor assembly is running under high heat conditions.

A plurality of fan blades I5 corresponding to the slots II project inwardly from one longitudinal edge of said slots, whereby, upon rotation of the rotor assembly, to create a circulation of air about the same. The fan blades I5 are the parts of the end bell which are struck out to form theslots II, remaining integral along one edge, and being bent inwardly therefrom.

At the end of the rotor opposite the res stance end bell 5, there is a projection of the conductor bars I I). The projecting portions of said conductor bars I0 engage, as a row, about a securing ring ll, and the bars are welded to said ring, as at II. There is a small gap between the se- 3 curing ring I. and the adjacent end of the rotor I, and a spacer bead it of annular configuration is engaged in said gap.

The rotor l is formed with a plurality of circumferentially spaced cooling bores I! therethrough from end to end in parallel relationship about the rotor axis; there being corresponding ports 20 and 2| in the endwall i of the end bell 5. and the securing ring Ii, respectively.

A pair of opposed ones of the ports 2| in the securing ring it are enlarged to receive dowels 22 which also project into the corresponding bore ll, whereby to maintain the ring it against rotation with respect to said rotor I.

With the conductor bars I! amxed at one end to the resistance end bell 5, and at the other end to the securing ring It, the parts of the rotor assembly are effectively maintained against any accidental axial separation. Additionally, the structural arrangement is such as to prevent any relative rotation between said parts.

When the rotor assembly is shaft mounted in an A. C. induction motor of high torque type. and the motor is running, the current induced in the conductor bars I feeds therealong to the resistance end bell 5, and wherein such current causes relatively high heating of said end bell. However, by reason oi the relatively great surface area of the end bell which includes the fan blades IS, the heat is dissipated rapidly and effectively; such heat dissipation being facilitated or accelerated by reason of the fan action.

The fan blades create an air circulation not only on the end bell but also through the cooling bores 09 and the slots l I; all to the better dissipation of the heat resultant from the induced current fed to the resistance end bell.

When the rotor assembly is operating under high heat conditions the resistance end bell and corresponding parts of, the conductor bars l0 are not subject to undesirable distortion; this for the reason that the flange 3 maintains the concentricity of the end bell. while the retention ring l4 prevents outward bowing or buckling of adjacent parts of the conductor bars III.

From the foregoing description it will be readily seen that t ere has been produced such a device as substantiall fulfills the objects of the invention. as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the ap ended claims.

Having thus described the invention, the following is claimed as new and useful, and upon which Letters Patent are desired:

1. A rotor assembly comprising a rotor including circumferentially spaced conductor bars extending lengthwise to and beyond one end of the rotor, a resistance end bell mounted at its closed end adjacent said one end of the rotor co-axially therewith, the end bell having a plurality of circumferentially spaced slots therein, the conductor bars projecting through corresponding slots and electrically connected to said end bell, and fan blades on the end bell in circumferentially spaced relation; the fan blades being adjacent and corresponding to the slots, in which said fan blades connect to the end bell along one longitudinal edge of the corresponding slot and in which said fan blades are integral with the end bell and comprise portions thereof cut on all edges but one and bent out to form said slots.

2. A rotor assembly, as in claim 1, in which the fan blades extend inwardly from the end bell toward the rotor axis.

3. A rotor assembly comprising a rotor including circumferentially spaced conductor bars extending lengthwise to and beyond one end of the rotor, a resistance end bell mounted at its closed end adjacent said one end of the rotor co-axially therewith and in outwardly flaring relation, said and bell having a circumferential row of slots therein, the slots being formed by portions of the end bell cut through on all edges but one and thence bent inward along the remaining uncut edges to provide fan blades, and the conductor bars projecting through corresponding slots and electrically connected to said end hell.

4. A rotor assembly comprising a rotor including circumferentially spaced conducto bars extending lengthwise to and beyond one end of the rotor, a resistance end bell mounted at said one end of the rotor and extending axially therefrom in outwardly flaring relation, said end bell having a circumferential row of slots therein, the slots being formed by portions of the end bell cut through on all edges but one and thence bent inward along the remaining uncut edges to provide fan blades, and the conductor bars projecting through corresponding slots and electrically connected to said end bell; the end bell including an outwardly extending annular flange at its free end, the adjacent portions of the conductor bars being bent outward and electrically connected to said flange.

5. A rotor assembly, as in claim 4, in which said outwardly bent portions of the bars are connected to the flange in substantially equally spaced relation.

6. A rotor assembly comprising a rotor including circumferentially spaced conductor bars extending lengthwise to and beyond one end of the rotor, a resistance end bell mounted at said one end of the rotor and extending axially therefrom in outwardly flaring relation, said end bell having a circumferential row of slots therein,'and the conductor bars projecting through corresponding slots and thence out-turned, the end bell having an annular, outwardly extending flange thereon, and means separately electrically connecting the out-turned portions of the bars to said flange.

7. A rotor assembly, as in claim 6, in which the conductor bars are in pairs, a pair projecting through each slot, and said out-turned portions of each pair of bars diverging outwardly to position said portions in substantially equally spaced relation on the flange.

ROBERT G. LE TOURNEAU.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Num er Name Date 920 798 Wiard May 4, 1909 1,038,110 Foss Sept. 10, 1912 

